1. Field of the Invention
The invention relates to offshore drilling and production operations and is specifically directed to drilling and production tensioners and risers assembled using the tensioners.
2. Description of Related Art
A marine riser system is employed to provide a conduit from a floating vessel at the water surface to the blowout preventer stack or, production tree, which is connected to the wellhead at the sea floor. A tensioning system is utilized to maintain a variable tension to the riser string alleviating the potential for compression and in turn buckling or failure.
Historically, conventional riser tensioner systems have consisted of both single and dual cylinder assemblies with a fixed cable sheave at one end of the cylinder and a movable cable sheave attached to the rod end of the cylinder. The assembly is then mounted in a position on the vessel to allow convenient routing of wire rope which is connected to a point at the fixed end and strung over the movable sheaves. A hydro/pneumatic system consisting of high pressure air over hydraulic fluid applied to the cylinder forces the rod and in turn the rod end sheave to stroke out thereby tensioning the wire rope and in turn the riser.
The number of tensioner units employed is based on the tension necessary to maintain support of the riser and a percentage of overpull which is dictated by met-ocean conditions i.e., current and operational parameters including variable mud weight, etc.
Normal operation of these conventional type tensioning systems have required high maintenance due to the constant motion producing wear and degradation of the wire rope members. Replacing the active working sections of the wire rope by slipping and cutting raises safety concerns for personnel and has not proven cost effective. In addition, available space for installation and, the structure necessary to support the units including weight and loads imposed, particularly in deep water applications where the tension necessary requires additional tensioners poses difficult problems for system configurations for both new vessel designs and upgrading existing vessel designs.
Recent deepwater development commitments have created a need for new generation drilling vessels and production facilities requiring a plethora of new technologies and systems to operate effectively in deep water and alien/harsh environments. These new technologies include riser tensioner development where direct acting cylinders are utilized.
Current systems as manufactured by Hydralift employ individual cylinders arranged to connect one end to the underside of the vessel sub-structure and one end to the riser string. These direct acting cylinders are equipped with ball joint assemblies in both the rod end and cylinder end to compensate for riser angle and vessel offset. Although this arrangement is an improvement over conventional wire rope systems, there are both operational and configuration problems associated with the application and vessel interface. For example, one problem is the occurrence of rod and seal failure due to the bending induced by unequal and non-linear loading caused by vessel roll and pitch. Additionally, these systems cannot slide off of the wellbore centerline to allow access to the well. For example, the crew on the oil drilling vessel is not able to access equipment on the seabed floor without having to remove and breakdown the riser string.
The tensioner system of the present invention is an improvement over existing conventional and direct acting tensioning systems. Beyond the normal operational application to provide a means to apply variable tension to the riser, the system provides a number of enhancements and options including vessel configuration and its operational criteria.
The tensioner system has a direct and positive impact on vessel application and operating parameters by extending the depth of the water in which the system may be used and operational capability. In particular, the system is adaptable to existing medium class vessels considered for upgrade by reducing the structure, space, top side weight and complexity in wire rope routing and maintenance, while at the same time increasing the number of operations which can be performed by a given vessel equipped with the tensioner system.
Additionally, the present invention extends operational capabilities to deeper waters than conventional tensioners by permitting increased tension while reducing the size and height of the vessel structure, reducing the amount of deck space required for the tensioner system, reducing the top-side weight, and increasing the oil drilling vessel""s stability by lowering its center of gravity.
Moreover, the tensioner of the present invention is co-linearly symmetrical with tensioning cylinders. Therefore, the present tensioner eliminates offset and the resulting unequal loading that causes rapid rod and seal failure in some previous systems.
The tensioner of the present invention is also radially arranged and may be affixed to the vessel at a single point. Therefore, the tensioner may be conveniently installed or removed as a single unit through a rotary table opening, or disconnected and moved horizontally while still under the vessel.
The tensioner of the present invention further offers operational advantages over conventional methodologies by providing options in riser management and current well construction techniques. Applications of the basic module design are not limited to drilling risers and floating drilling vessels. The system further provides cost and operational effective solutions in well servicing/workover, intervention and production riser applications. These applications include all floating production facilities including, tension leg platform (T.L.P.) floating production facility (F.P.F.) and production spar variants. The system when installed provides an effective solution to tensioning requirements and operating parameters including improving safety by eliminating the need for personnel to slip and cut tensioner wires with the riser suspended in the vessel moonpool. An integral control and data acquisition system provides operating parameters to a central processor system which provides supervisory control.
The present invention is also directed to a method of assembling a string of production riser, or production riser, for drill stem testing while the larger string of drilling riser, referred to herein as the drilling riser, is still suspended from the vessel, and preferably, still connected to the wellhead. Therefore, the amount of time, and thus money, required to prepare for the drill stem test is substantially reduced. While the background of method of assembling a production riser will be discussed in greater detail, it is to be understood that the methods of the present invention include assembling a drilling riser.
Generally, a well is first drilled from a drilling vessel or drilling platform having one or more derricks for supporting the drilling riser and other drilling equipment. After drilling is completed, the well is xe2x80x9cclosed offxe2x80x9d using valves or other equipment. The drilling riser is then disassembled. The production riser is then assembled, usually utilizing the same derrick and equipment. This is especially true in vessels having only one fill size derrick that can support the weight of the riser. Both the drilling riser and the production riser consist of tubulars, e.g., casing, attached end to end and extended from the wellhead to the drilling or production facility, e.g., vessel or platform.
Alternatively, in drilling vessels having two derricks, the second derrick may be utilized to assemble the production riser. After the production riser is assembled, it is attached to the wellhead and a drill stem test is performed. The drill stem test is an evaluation of unrestricted flow of hydrocarbon, e.g., oil or gas, from the well and into shipboard tanks to facilitate determining the hydrocarbon reservoir""s size and propensity to flow, e.g., the pressure differential between the well and the tanks capturing the flowing hydrocarbon.
Present methods and applications of this process require either two derricks on the drilling or production vessel or platform, or, require substantially amounts of time, and thus money, to detach and disassemble the drilling riser from the wellhead, and then assemble and attach the production riser to the wellhead using a single derrick.
The methods of the present invention overcome this problem because a derrick is not required to assemble the riser. Instead, a crane,jack knife hoisting rig, or other lifting device smaller than a full size derrick may be used. Additionally, the methods of the present invention provide the advantages of: providing a means to run the riser from the unused rig floor aboard a drilling or production facility, without the use of a standard capacity derrick; includes a system that is modular in construction, transportation, and assembly; providing interchangeability with other drilling or production facilities; permitting assembly of the production riser while the drilling riser is still in use and vice versa; reducing the amount of time that the wellhead is xe2x80x9cidle,xe2x80x9d i.e., that either a drilling riser or production riser is in use; reducing the amount of extra equipment that is needed by the facility in making the rig floor ready for use; providing sufficient tension to the long string of the riser in deepwater over extended periods of time; providing a means to maintain the riser in constant tension, with, if necessary, overpull, while the riser is in service; providing the capability to accommodate angular offset between the riser and the vessel induced by vessel motion; and providing the capability to accommodate axial torque induced in the riser string in the event the drilling or production vessel rotates around the wellhead due to weather and sea conditions.
Further, the methods of assembling a riser using the tensioner of the present invention permit the assembly of the production riser without having to disconnect, or disassemble the drilling riser from the wellhead, and vice versa. Therefore, the drilling tubulars and riser can subsequently be disconnected from the wellhead and the vessel moved to position the pre-assembled production riser into to place and secured to the wellhead, and vice versa, thereby resulting in time, and thus, cost savings.
The foregoing advantages have been obtained through the present tensioner comprising: at least one mandrel; at least one upper flexjoint swivel assembly in communication with the at least one mandrel; at least one manifold in communication with the at least one upper flexjoint swivel assembly, the at least one manifold having a first radial fluid band and a second radial fluid band; at least one tensioning cylinder having a blind end, a rod end, and at least one transfer tubing, the blind end being in communication with the first radial fluid band, the transfer tubing being in communication with the second radial fluid band and the rod end being in communication with at least one flexjoint bearing; and a base in communication with the at least one flexjoint bearing.
A further feature of the tensioner is that the manifold may include a third radial fluid band, the third radial fluid band being in communication with either the blind end or the at least one transfer tubing. Another feature of the tensioner is that the first and third radial fluid bands may be in communication with the at least one transfer tubing and the second radial fluid band may be in communication with the blind end of the at least one tensioning cylinder. An additional feature of the tensioner is that the tensioner may include six tensioning cylinders, wherein at least one tensioning cylinder may be in communication with a first control source and at least one tensioning cylinder may be in communication with a second control source. Still another feature of the tensioner is that the first control source and second control source may be in communication with the same tensioning cylinder. A further feature of the tensioner is that the tensioner may include a hang-off donut. Another feature of the tensioner is that the hang-off donut may be disposed on the mandrel or along the tensioning cylinders, e.g., below the blind end of the tensioning cylinders which captures each of the tensioning cylinders and allows for the transference of axial tension load from the cylinder casing to the mandrel and then directly to the rig structure. An additional feature of the tensioner is that the blind end may be connected to the manifold by at least one sub seal. Still another feature of the tensioner is that each of the at least one tensioning cylinder may include at least one cylinder head. Yet another feature of the tensioner is that the first, second, and third radial fluid bands may each be in communication with a transducer. A further feature of the tensioner is that the tensioner may include at least two tensioning cylinders. Another feature of the tensioner is that the tensioner may include two radial fluid bands in communication with at least one transfer tubing and one radial fluid band in communication with the blind end of each of the at least one tensioning cylinder. An additional feature of the tensioner is that a sub-manifold may be included between the blind end of the tensioning cylinder and the manifold, thereby permitting remotely operated valves to be disposed in the communication channels between the tensioning cylinders and the manifold making it possible to isolate any single or combination of tensioning cylinders for operation, maintenance and Riser Disconnect Management Systems (RDMS) procedures. Still another feature of the tensioner is that a swivel feature may be incorporated either within or in the area of the manifold or upper flexjoint swivel assembly, thereby providing a means to remotely turn the entire tensioner to remove torsional stresses in the riser string that result from the vessel changing heading. A further feature of the tensioner is that the tensioner may further comprise at least one lower flexjoint swivel assembly in communication with the at least one tensioning cylinder and the base.
The foregoing advantages have also been achieved through the present tensioner comprising: at least one mandrel having a first mandrel end and a second mandrel end; at least one upper flexjoint swivel assembly having a first upper flexjoint swivel assembly end and a second upper flexjoint swivel assembly end; at least one manifold having a first manifold surface and a second manifold surface; at least one tensioning cylinder having a blind end, a rod end, and at least one flexjoint bearing in communication with the rod end; and a base, wherein the second mandrel end is connected to the first upper flexjoint swivel assembly end, the second upper flexjoint swivel assembly end is connected to the first manifold surface, the second manifold surface is connected to the blind end, and the rod end and the at least one flexjoint bearing are connected to the base.
A further feature of the tensioner is that tensioner may further include at least one lower flexjoint swivel assembly having a first lower flexjoint swivel assembly end and a second lower flexjoint swivel assembly end, wherein the rod end is connected to the first lower flexjoint swivel assembly end and the second lower flexjoint swivel assembly end is connected to the base. A further feature of the tensioner is that the at least one tensioning cylinder may include at least one transfer tubing, the at least one transfer tubing being in communication with the manifold. Another feature of the tensioner is that the manifold may include two radial fluid bands in communication with the at least one transfer tubing and one radial fluid band in communication with the blind end of the at least one tensioning cylinder. An additional feature of the tensioner is that the tensioner may include six tensioning cylinders, wherein at least one of the tensioning cylinders is in communication with a first control source and at least one tensioning cylinder is in communication with a second control source. Still another feature of the tensioner is that the first control source and the second control source may be in communication with the same tensioning cylinder. A further feature of the tensioner is that the tensioner may include a hang-off donut. Another feature of the tensioner is that the at least one manifold may include at least two radial fluid bands. An additional feature of the tensioner is that at least one of the at least two radial fluid bands may be in communication with the blind end and at least one of the at least two radial fluid bands may be in communication with the rod end.
The foregoing advantages have also been achieved through the present tensioner comprising: at least one mandrel, at least one upper flexjoint swivel assembly, at least one manifold, at least one tensioning cylinder, and a base, the at least one tensioning cylinder includes a blind end in communication with the at least one manifold and a rod end in communication with the base; wherein the at least one mandrel, the at least one upper flexjoint swivel assembly, the at least one manifold, the at least one tensioning cylinder, and the base are assembled to form a unitary, co-linear tensioner.
A further feature of the tensioner is that the tensioner may further comprise at least one lower flexjoint swivel assembly. An additional feature of the tensioner is that the at least one mandrel may be connected to the at least one upper flexjoint swivel assembly, the at least one upper flexjoint swivel assembly being connected to the at least one manifold, the at least one manifold being connected to the at least one tensioning cylinder, the at least one tensioning cylinder being connected to the at least one lower flexjoint swivel assembly, and the at least one lower flexjoint swivel assembly being connected to the base.
The foregoing advantages have also been achieved through the present method for assembling a riser having a plurality of tubulars comprising the steps of: (a) providing a tensioner having a first tensioner end, a second tensioner end, a retracted position, an extended position, at least one mandrel, at least one upper flexjoint swivel assembly in communication with the at least one mandrel, at least one manifold in communication with the at least one upper flexjoint swivel assembly, the at least one manifold having a first radial fluid band and a second radial fluid band, at least one tensioning cylinder having a blind end, a rod end, and at least one transfer tubing, the blind end being in communication with the first radial fluid band, the transfer tubing being in communication with the second radial fluid band, and a base in communication with the rod end of each of the at least one tensioning cylinder; (b) providing a drilling or production facility having a rig floor and a moonpool disposed below the rig floor, the rig floor including at least one rig floor slip having a rig floor slip opened position and a rig floor slip closed position; (c) inserting the tensioner through the at least one rig floor slip, through the rig floor, and into the moonpool; (d) connecting the tensioner to the rig floor; (e) inserting a first tubular through the at least one rig floor slip, through the rig floor, through the tensioner, and into the moonpool; (f) disposing the at least one rig floor slip around the first tubular and moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position, whereby the first tubular is maintained in place by the at least one rig floor slip; (g) connecting a second tubular to the first tubular thereby forming a riser having a plurality of tubulars; (h) moving the at least one rig floor slip from the rig floor closed position to the rig floor opened position; (i) inserting the second tubular through the at least one rig floor slip, through the rig floor, through the tensioner, and into the moonpool; (j) moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position, whereby the riser is maintained in place by the at least one rig floor slip; (k) releasably securing the base of the tensioner to the first tubular; (l) connecting a third tubular to the second tubular; (m) moving the at least one rig floor slip from the rig floor closed position to the rig floor opened position; (n) inserting the third tubular through the at least one rig floor slip, through the rig floor, through the tensioner, and into the moonpool, thereby moving the tensioner from the retracted position to the extended position; (o) moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position; (p) releasing the base of the tensioner from the first tubular, whereby the riser is maintained in place by the at least one rig floor slip; (q) moving the tensioner from the extended position to the retracted position; (r) releasably securing the base of the tensioner to the second tubular; (s) connecting a fourth tubular to the third tubular; (t) moving the at least one rig floor slip from the rig floor closed position to the rig floor opened position; (u) inserting the fourth tubular through the at least one rig floor slip, through the rig floor, through the tensioner, and into the moonpool, thereby moving the tensioner from the retracted position to the extended position; (v) moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position; (w) releasing the base of the tensioner from the second tubular, whereby the riser is maintained in place by the at least one rig floor slip; (x) moving the tensioner from the extended position to the retracted position; and (y) releasably securing the base of the tensioner to the third tubular.
A further feature of the method for assembling a riser having a plurality of tubulars is that steps (s) through (y) may be repeated with at least one additional tubular until the riser has a predetermined length. Another feature of the method for assembling a riser having a plurality of tubulars is that the method may further include the steps of: connecting a final tubular to the riser; and inserting the final tubular through the at least one rig floor slip, through the rig floor and the tensioner, and into the moonpool. An additional feature of the method for assembling a riser having a plurality of tubulars is that the tensioner may be moved from the extended position to the retracted position, by activating at least one control source in communication with the tensioner. Still another feature of the method for assembling a riser having a plurality of tubulars is that the tensioner and each of the plurality of tubulars may be inserted through the rig floor and into the moonpool by lifting and positioning the tensioner and each of the plurality of tubulars with a crane. A further feature of the method for assembling a riser having a plurality of tubulars is that the tensioner and each of the plurality of tubulars may be inserted through the rig floor and into the moonpool by lifting and positioning the tensioner and each of the plurality of tubulars with a jack knife hoisting rig. Another feature of the method for assembling a riser having a plurality of tubulars is that the tensioner may be connected to the rig floor by removing the at least one rig floor slip and resting the tensioner on the rig floor. An additional feature of the method for assembling a riser having a plurality of tubulars is that the tensioner may be connected to the rig floor by placing the tensioner in communication with a rotating bearing disposed on the rig floor. Still another feature of the method for assembling a riser having a plurality of tubulars is that at least one spider beam may be inserted and at least one subsea appliance is disposed on the at least one spider beam and connected to the first tubular prior to the connection of the second tubular to the first tubular. A further feature of the method for assembling a riser having a plurality of tubulars is that the at least one spider beam may be removed after the connection of the at least one subsea appliance is connected to the first tubular.
The foregoing advantages have also be achieved through the present method for assembling a riser having a plurality of tubulars comprising the steps of: (a) providing a tensioner having a first tensioner end, a second tensioner end, a retracted position, an extended position, at least one mandrel, at least one upper flexjoint swivel assembly in communication with the at least one mandrel, at least one manifold in communication with the at least one upper flexjoint swivel assembly, the at least one manifold having a first radial fluid band and a second radial fluid band, at least one tensioning cylinder having a blind end, a rod end, and at least one transfer tubing, the blind end being in communication with the first radial fluid band, the transfer tubing being in communication with the second radial fluid band, and a base in communication with the rod end of each of the at least one tensioning cylinder; (b) providing a drilling or production facility having a rig floor and a moonpool disposed below the rig floor, the rig floor having at least one rig floor slip having a rig floor slip opened position and a rig floor slip closed position; (c) inserting a first tubular through the at least one rig floor slip, through the rig floor, and into the moonpool; (d) moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position, whereby the first tubular is maintained in place by the at least one rig floor slip; (e) connecting a second tubular to the first tubular thereby forming a riser having a plurality of tubulars; (f) moving the at least one rig floor slip from the rig floor closed position to the rig floor opened position; (g) inserting the second tubular through the at least one rig floor slip, through the rig floor, and into the moonpool; (h) moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position, whereby the riser is maintained in place by the at least one rig floor slip; (i) providing at least one spider beam, the at least one spider beam having at least one spider beam slip having a spider beam slip opened position and a spider beam slip closed position; (j) disposing the at least one spider beam slip around the riser and moving the at least one spider beam slip from the spider beam slip opened position to the spider beam slip closed position; (k) moving the at least one rig floor slip from the rig floor slip closed position to the rig floor slip opened position, whereby the riser is maintained in place by the at least one spider beam slip; (l) lowering the tensioner over the riser, through the rig floor, and into the moonpool, whereby the riser passes through the tensioner; (m) connecting the tensioner to the rig floor; (n) releasably securing the base of the tensioner to the riser; and (o) moving the at least one spider beam slip from the spider beam slip opened position to the spider beam slip closed position, whereby the riser is maintained in place by the tensioner.
A further feature of the method for assembling a riser having a plurality of tubulars is that after step (h), steps (e) through (h) may be repeated with at least one additional tubular until the production riser has a predetermined length. Another feature of the method for assembling a riser having a plurality of tubulars is that the riser may include at least 10 tubulars. An additional feature of the method for assembling a riser having a plurality of tubulars is that the riser may include at least 50 tubulars. Still another feature of the method for assembling a riser having a plurality of tubulars is that the tensioner and each of the plurality of tubulars may be inserted through the rig floor and into the moonpool by lifting and positioning the tensioner and each of the plurality of tubulars with a crane. A further feature of the method for assembling a riser having a plurality of tubulars is that the tensioner and each of the plurality of tubulars may be inserted through the rig floor and into the moonpool by lifting and positioning the tensioner and each of the plurality of tubulars with a jack knife hoisting rig. Another feature of the method for assembling a riser having a plurality of tubulars is that step (e) may be achieved by: hoisting and positioning the second tubular above the first tubular and connecting the second tubular to the first tubular. An additional feature of the method for assembling a riser having a plurality of tubulars is that the tensioner may be connected to the rig floor by moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position. Still another feature of the method for assembling a riser having a plurality of tubulars is that the tensioner may be connected to the rig floor by resting the tensioner on the rig floor. A further feature of the method for assembling a riser having a plurality of tubulars is that the tensioner may be connected to the rig floor by placing the tensioner in communication with a rotating bearing disposed on the rig floor.
The foregoing advantages have also been achieved through the present method for assembling a riser having a plurality of tubulars comprising the steps of: (a) providing a tensioner having a first tensioner end, a second tensioner end, a retracted position, an extended position, at least one mandrel, at least one upper flexjoint swivel assembly in communication with the at least one mandrel, at least one manifold in communication with the at least one upper flexjoint swivel assembly, the at least one manifold having a first radial fluid band and a second radial fluid band, at least one tensioning cylinder having a blind end, a rod end, and at least one transfer tubing, the blind end being in communication with the first radial fluid band, the transfer tubing being in communication with the second radial fluid band, and a base in communication with the rod end of each of the at least one tensioning cylinder; (b) providing a drilling or production facility having a rig floor and a moonpool disposed below the rig floor, the rig floor having at least one rig floor slip having a rig floor slip opened position and a rig floor slip closed position; (c) inserting a first tubular through the at least one rig floor slip, through the rig floor, and into the moonpool; (d) moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position, whereby the first tubular is maintained in place by the at least one rig floor slip; (e) providing at least one spider beam, the at least one spider beam having at least one spider beam slip having a spider beam slip opened position and a spider beam slip closed position; (f) disposing the at least one spider beam slip around the first tubular and moving the at least one spider beam slip from the spider beam slip opened position to the spider beam slip closed position; (g) moving the at least one rig floor slip from the rig floor slip closed position to the rig floor slip opened position, whereby the first tubular is maintained in place by the at least one spider beam slip; (h) lowering the tensioner over the first tubular, through the rig floor, and into the moonpool, whereby the first tubular passes through the tensioner; (i) connecting the tensioner to the rig floor; (j) releasably securing the base of the tensioner to the first tubular; (k) moving the at least one spider beam slip from the spider beam slip closed position to the spider beam slip opened position, whereby the first tubular is maintained in place by the tensioner; (l) connecting a second tubular to the first tubular thereby forming a riser having a plurality of tubulars; (m) moving the at least one rig floor slip from the rig floor closed position to the rig floor opened position; (n) inserting the second tubular through the at least one rig floor slip, through the rig floor, through the tensioner, and into the moonpool, thereby moving the tensioner from the retracted position to the extended position; (o) moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position; (p) releasing the base of the tensioner from the riser, whereby the riser is maintained in place by the at least one rig floor slip; (q) moving the tensioner from the extended position to the retracted position; and (r) releasably securing the base of the tensioner to the riser.
A further feature of the method for assembling a riser having a plurality of tubulars is that the method further includes the step of: (s) repeating steps (l) through (r) with at least one additional tubular until the riser has a predetermined length. Another feature of the method for assembling a riser having a plurality of tubulars is that the second tubular may be connected to the first tubular to form the riser having a plurality of tubulars prior to step (h). An additional feature of the method for assembling a riser having a plurality of tubulars is that at least two additional tubulars may be connected to the riser prior to step (h) by: moving the at least one rig floor slip from the rig floor closed position to the rig floor opened position; connecting the at least one additional tubular to the riser; inserting the at least one additional tubular through the at least one rig floor slip, through the rig floor, and into the moonpool; moving the at least one rig floor slip from the rig floor slip opened position to the rig floor slip closed position, whereby the riser is maintained in place by the at least one rig floor slip; repeating the above steps with at least one additional tubular until the production riser has a predetermined length. Still another feature of the method for assembling a riser having a plurality of tubulars is that the method may further comprise the step of: removing the at least one spider beam after step (k). A further feature of the method for assembling a riser having a plurality of tubulars is that the method may further comprise the steps of: connecting a final tubular to the production riser; and inserting the final tubular through the at least one rig floor slip, through the rig floor, and into the moonpool.